In an ink jet recording apparatus, inks of different colors such as yellow, cyan, magenta and black are supplied to a recording head. The recording head discharges the different colors of ink to form dots on a recording medium, the dots forming a color image on the recording medium. One basic characteristic of an ink jet recording apparatus that is often of concern to a user is color reproducibility. Color reproducibility represents the magnitude of the difference between the color of the original and the color of the image formed on the recording medium generated from the original. The better the color reproducibility is, namely, the smaller the magnitude of the difference between the original and the image formed on the recording medium, the closer the color of an image formed by the ink jet recording apparatus will be to the color of the original.
If the number of different color inks discharged onto the recording medium is large (that is, if inks of many colors contribute to the image-recording), the color reproducibility of each color improves. Consequently, in some conventional ink jet recording apparatuses many ink cartridges are mounted and many inks are pre-stocked for example as shown in JP-A-2001-219585 and JP-A-6-293142.
In ink jet recording apparatuses in which many ink cartridges are mounted individually, an ink of every color has to be stocked irrespective of the frequency of use of the different colors. Consequently, the running cost of the ink jet recording apparatus increases. To avoid this problem, an ink jet printing apparatus has been proposed wherein inks of predetermined colors are prepared by mixing the colors in advance and then pouring the colors into ink cartridges as described in JP-A-6-293142. However, in an ink jet recording apparatus which employs such an ink preparation technique, the apparatus includes a separate device provided for mixing ink. As such, the ink jet recording apparatus becomes large and its manufacturing cost greatly increases.